Effects of size grading on growth performance, survival rate and cannibalism in Russian Sturgeon (Acipenser gueldenstaedtii) larvae under small-scale hatchery conditions

Abstract

Sturgeon aquaculture is important due to the value of their caviar and meat as well as its ecological importance. The current study focused on the effects of different size groups on the final mean weight, specific growth rate, survival rate and cannibalism of Russian sturgeon (Acipenser guelden-staedtii) larvae. The groups were graded with homogeneous small-size larvae in the first group, 50% small and 50% large-size heterogeneous larvae in the second group, and homogeneous large -size larvae in the third group. The highest specific growth rates in each group occurred between days 28-35. After 35 days, the specific growth rate (SGR) in all groups dramatically reduced com-pared to the first week. The SGR of the larvae were not significantly affected by size (p>0.05). Mor-talitiy were high during the first week in all groups, but, decreased as the larvae grew larger during the fourth weeks. At the end of the study, the survival rates were 30% for the small-size, 53% het-erogeneous-size, and 64% for the large-size groups. The highest cannibalism rate in the present study occurred in heterogeneous-size group. However, the literature shows cannibalism rates to not be high for any groups of sturgeon. Size grading in the early period may negatively affect the survival rate and growth performance of larvae. Therefore, maintaining optimum larval rearing con-ditions such as stocking density, and feeding strategy may support higher survival and growth performance, in larvae that are newly acclimated to exogenous feeding.